The X-20: America’s Space Fighter

Everyone knows space fighters are an absurd idea, right? It’s practically the first rule of hard science fiction: this isn’t Star Wars you’re writing, so no fighters, period. They make no economic or military sense, and they’re exceedingly small and vulnerable, and they’re not nearly as maneuverable as you’d think because space has no air to fly in. Just terrible, really. Your best option for small craft is probably unmanned laser satellites, or something.

It turned out that the US and USSR both took a while to get that memo. The history of the early Space Age is littered with attempts to weaponize low Earth orbit (and beyond!), with plans for, variously, cannon-armed space stations, manned spy satellites, anti-satellite missiles, and an Army base on the freakin’ Moon1. Mixed in with the proposals were what essentially amounted to orbital fighter craft: the Soviets had the Spiral2 spaceplane, and the Americans had the X-20 Dyna-Soar—the subject of today’s exploration.

Simple schematic of the X-20, showing the delta-wing design.

I guess if you want to get into the weeds here, it was less an X-Wing and more a proto-Space Shuttle operated by the military, but still. My point stands. The X-20, developed by Bell Aircraft and later Boeing between 1957-ish and 1963, was intended to be a multirole reusable space vehicle for the United States Air Force, conducting peacetime operations such as strategic reconnaissance, space rescue, and maintenance of on-orbit assets. If war broke out, it would have served instead as a satellite interceptor and intercontinental nuclear bomber. It was pretty much the jack-of-all-trades of Earth-orbit operations, and it needed to be, since the engineers at Bell and Boeing were always struggling to find some new way to justify their project’s enormous budget.

The development of Dyna-Soar actually started in Nazi Germany, towards the beginning of World War II. The Luftwaffe was soliciting bids for the Amerika Bomber3 project, and engineers Eugen Sanger and Irene Bredt submitted by far the strangest proposal: a sled-launched rocket plane which would soar to the edge of space, release a four-ton bomb over New York, and then land somewhere in the territory of the Japanese Empire. This was the “Silbervogel,” or “silver bird.” Someday I will write a dedicated blog post on it, but what’s important right now is that two other German rocket scientists, Walter Dornberger and Krafft Ehricke, brought the concept to America after the war. In 1952 they proposed a vertical-launch version of the Silbervogel to Bell Aircraft, calling their design the “Bomber Missile.”

This concept eventually split off into three varieties of rocket-boosted suborbital spaceplane. These comprised a bomber and a reconnaissance craft, plus a technology testbed; in October 1957 they were all merged back together into the Dyna-Soar. At this point Dyna-Soar remained suborbital-only, with the end goal being an operational intercontinental strike force by 1974—combining the speed and range of an ICBM with the accuracy and flexibility of a bomber. In 1958 the Air Force began the process of selecting a contractor to complete and build the spaceplane. By 1959 it came down to a heated struggle between Bell and Boeing, who had nearly identical proposals, and in a shocking upset Boeing was selected, rather than Bell which had actually incubated and developed the Dyna-Soar project up to this point.

The X-20 launches atop one of the many, many boosters that were under consideration. Note the wings on the bottom, for stability.

Sometime around 1960 or 1961 the focus shifted from suborbital flights to orbital ones. Wikipedia and Encyclopedia Astronautica are unclear as to when, exactly, this transition took place, but the final version leading up to 1963 was very much an orbital craft. It was a visionary design, foreshadowing later developments such as the Space Shuttle; though it was considerably smaller, with a mass of five tons and a crew of one, it pioneered a similar flat-bottomed delta-wing layout. The structural frame was made from a nickel alloy similar to that used in the Mercury spacecraft, while molybdenum served as the material for the bottom surface. There was also a heat shield over the nose of the craft, blocking the window—the pilot would only have been able to see out the sides—and this only would have been jettisoned on the landing approach.

The X-20, about to land. Most or all Dyna-Soar missions were intended to end at Edwards AFB in California.

Notably, the X-20 did not have landing gear, the concern being that the rubber would melt during reentry. Instead it used retractable wire-brush skids, a little like those of the ME-163 rocket fighter of World War II. For takeoff it would have been placed in LEO by a two-stage system, comprising the Titan III4 booster, derived from an ICBM, and a powerful second stage, with a whopping two km/s delta-v even after the orbital insertion. The idea here was for the X-20 to perform major trajectory changes, making it far harder to anticipate and shoot down. To this end, the Air Force also suggested an exotic form of aerobraking, whereby the X-20 would dip into the upper atmosphere and leverage the air itself to change inclination—ordinarily a very expensive maneuver in terms of fuel. To my knowledge, no subsequent spacecraft have attempted to do this.

Development of the X-20 did get far enough for serious mission planning to take place. In 1964 the Air Force would have carried out a drop test from a B-52, and they intended to launch the first manned flight by 1966, contemporaneous with NASA’s Gemini program. Seven experienced pilots made the shortlist to fly these missions. Among them was a young Korean War veteran, Neil Armstrong, who of course never went on to accomplish anything of importance.

He was also involved in the X-15 program around the same time; it was a shame his career ended so early, the man had a lot of potential.

Had the X-20 program continued to fruition, it could well have had a long and decently successful career in military reconnaissance, with additional roles in satellite inspection, disabling hostile spacecraft, and carrying out rescue operations. A follow-up design called the X-20X would have entirely rearranged the interior, enabling it to carry four additional passengers for station ferry missions by the end of the 1960s.

Of course, the exceedingly costly X-20 program (to the tune of $5.5 billion in today’s money) ran into a problem quite common to these sorts of zany big-budget research projects: it lacked a clearly definable purpose. The Air Force had a plan to get into space and return, but very little to do while there. The reconnaissance role was already being fulfilled by cheap, expendable spy satellites, and with ICBMs becoming far more accurate and reliable, there was no serious need for a space bomber. Orbital rescue and satellite sabotage remained too fanciful to justify the cost on their own. The Secretary of Defense, Robert McNamara, saw all these problems quite clearly, and ultimately canceled it on December 10, 1963.

What came after? Well, as the decade went on there wasn’t much more interest in manned military spaceflight, save for the also-canceled Manned Orbiting Laboratory (derived from Gemini). The idea of a one-man space fighter was relegated to the fringes, never again being taken as seriously as it was in the Dyna-Soar years. Bell and Boeing’s reentry research proved quite useful, however, with the Space Shuttle building upon their aerodynamic data, and later on the European Space Agency loosely modeled their never-flown Hermes spaceplane after the X-20. Since the 2010s, the closest thing we’ve had is the X-375, an unmanned five-ton glider which flies top-secret orbital missions for the US Space Force. Exact specifications and possible armament are a mystery; hopefully it can carry a laser to zap stuff, because that would be pretty cool.

An X-37 on the tarmac in 2010.

Even more recently, I built my own version in Kerbal Space Program. Despite a different appearance, my K-21 design has a very similar mission profile to the X-20: launch atop a large booster stage, enter orbit, do spy stuff, and then glide back to the surface. It flies beautifully:

Behold the K-21! Complete with reconnaissance cameras (modded) and sometimes a missile (not modded, surprisingly).

The X-20 Dyna-Soar, despite its silly name, marked a pivotal advance in the history of orbital flight. It was a design ahead of its time, a fully functional spaceplane in an era when the Space Race contestants flew only conical or spherical capsules; the concept is even more impressive given the unknown aerodynamics involved, and the fact that for much of its existence, until April 1961, manned spaceflight still occupied the realm of the hypothetical. Suffice it to say that space history could have taken a markedly different course, had this project been given the go-ahead.

Further Reading:

  1. Project Horizon was a wild time. Its doom came about in a similar way to the X-20, actually: despite the engineers’ clear enthusiasm for the project, there wasn’t actually much of a point in military terms. This will be the subject of a later post!
  2. Spiral will get its own subsequent post, though it will probably be a lot shorter. Being a Soviet design project (and a poorly fleshed-out one, at that), there’s much less information to work with.
  3. Compass Games actually has a board game where you play the pilot of an Amerika Bomber. Sadly you cannot fly the Silbervogel.
  4. It took Boeing a while to settle on this one, though. Various other Titan rocket iterations were considered, as well as the Saturn I.
  5. Also by Boeing.

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